# -*- coding: utf-8 -*-#
#-------------------------------------------------------------------------------
# 建立者:        潘炎珍  
# Name:         demo11
# Description:
# Author:       98745
# Date:         2019/3/12
#-------------------------------------------------------------------------------

import numpy
import matplotlib.pyplot as plt
x=numpy.linspace(-6,6,1024)
plt.plot(x,-x**2,color='r',linestyle='solid')
plt.plot(x,-x**2+3,color='b',linestyle='dashed')
plt.plot(x,-x**2+6,color='k',linestyle='dashdot')
plt.show()